I have to calculate values of several equations in an application. For example, one these equations could be:
d = a + b*z + c*z (this is what is being displayed to the user, assume that 'a', 'b' and 'c' are provided as textboxes, assume that z is a hardcoded value for now)
Now, the user could enter a=1.5, b= -0.5 and c = -0.6 (or even 'a' could be negative)
So, I just tried a sample code for simple values but to no avail...
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
Dim val1, val2, val3_calculated, first, second As String
first = "8"
second = "3"
Dim arr(10) As String
arr(1) = "-"
arr(2) = "+"
val1 = TextBox1.Text
val2 = val1.Substring(0, 1)
If arr.Contains(val2) Then
val3_calculated = Eval("return first val2 second") // I tried using '&' operator as well
End If
MsgBox(val3_calculated)
Error:
But it throws an error saying that I am not using any databind control.
Concerns:
First of all, is it necessary to use this "eval" operator in here? Is there any way to keep "-0.5" with the sign in asp.net using vb? Can I do something else to make it work? (I would prefer a small piece of code for this).
Thank you:
Any help is highly appreciated. It is kinda urgent. Thanks a lot.
First of all, the Eval method is used to evaluate variables in conjunction with server controls.
Secondly, you would normally use an event handler like a Button Click as the method to either populate controls within your ASPX page or save to your data source.
Lastly, your statement to "evaluate" is not login as this is a subroutine method that returns nothing.
Given this, what are you trying to do?
Christopher Reed, MCT, MCPD, MCTS, Microsoft Specialist, MTA
"The oxen are slow, but the earth is patient."
KnowledgeisW...
0 Points
10 Posts
Do I have to use an Eval operator here?
Apr 21, 2012 07:21 PM|LINK
Hi everyone,
Problem:
I have to calculate values of several equations in an application. For example, one these equations could be:
d = a + b*z + c*z (this is what is being displayed to the user, assume that 'a', 'b' and 'c' are provided as textboxes, assume that z is a hardcoded value for now)
Now, the user could enter a=1.5, b= -0.5 and c = -0.6 (or even 'a' could be negative)
So, I just tried a sample code for simple values but to no avail...
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) Handles Button1.Click
Dim val1, val2, val3_calculated, first, second As String
first = "8"
second = "3"
Dim arr(10) As String
arr(1) = "-"
arr(2) = "+"
val1 = TextBox1.Text
val2 = val1.Substring(0, 1)
If arr.Contains(val2) Then
val3_calculated = Eval("return first val2 second") // I tried using '&' operator as well
End If
MsgBox(val3_calculated)
Error:
But it throws an error saying that I am not using any databind control.
Concerns:
First of all, is it necessary to use this "eval" operator in here? Is there any way to keep "-0.5" with the sign in asp.net using vb? Can I do something else to make it work? (I would prefer a small piece of code for this).
Thank you:
Any help is highly appreciated. It is kinda urgent. Thanks a lot.
Careed
All-Star
18798 Points
3649 Posts
Re: Do I have to use an Eval operator here?
Apr 21, 2012 08:36 PM|LINK
First of all, the Eval method is used to evaluate variables in conjunction with server controls.
Secondly, you would normally use an event handler like a Button Click as the method to either populate controls within your ASPX page or save to your data source.
Lastly, your statement to "evaluate" is not login as this is a subroutine method that returns nothing.
Given this, what are you trying to do?
"The oxen are slow, but the earth is patient."